An estimated 18.2 million people in the US, and 135 million people worldwide, have type 2 diabetes . Over time, and especially if left untreated, diabetes can lead to coronary artery disease, amputation, blindness, and renal failure , among other complications.

There are many well-established risk factors for developing type 2 diabetes, a major one being obesity . Recent studies have suggested an association between dairy intake and lower body weight. A number of studies have also suggested that consuming dairy products is associated with a lower risk of insulin resistance. Insulin is required for blood sugar to enter cells. As the cells become resistant to the effects of insulin, sugar begins to build up in the blood. Insulin resistance is the first step on the way to type 2 diabetes.

A new study in the May 9, 2005 issue of the Archives of Internal Medicine is the first to examine the direct relationship between dairy intake and the development of type 2 diabetes. The study found that consuming dairy products, particularly low-fat dairy products, was associated with a reduced risk of diabetes.

About the Study

This study included 41,254 male participants who had no previous history of diabetes, heart disease, or cancer. The participants were all part of the Health Professionals Follow-up Study, an ongoing study of male health professionals who were between the ages of 40 and 75 at the start of the study in 1986.

Participants completed food frequency questionnaires in 1986, 1990, and 1994, that asked about their usual intake of roughly 130 different foods and beverages. Every two years the participants also provided information on body weight, medication use, and medical conditions. The researchers followed the participants for 12 years and then assessed the relationship between dairy intake and the development of type 2 diabetes.

The Findings

During the study period, a total of 1,243 participants developed type 2 diabetes. After adjusting for age, the men who consumed the most dairy (> 2.9 servings per day) were 18% less likely to develop diabetes than those who consumed the least dairy (< 0.9 servings per day). After further adjustment for dietary risk factors such as intake of cereal fiber, trans-fat, and saturated fat, this difference became even greater: men who consumed the most dairy were now 23% less likely to develop diabetes than those who consumed the least.

Overall, every serving-per-day increase in dairy resulted in a 9% lower risk for type 2 diabetes. When compared by fat content, low-fat dairy products, especially skim milk, had the strongest association with lowered diabetes risk.

One limitation of this study is that the ethnic background of the participants was not mentioned, an important consideration since dairy could have a different affect on people depending on their genetic make-up. Interestingly, diabetes is more common among certain ethnic groups, including African Americans, Latinos, and Native Americans, populations that are also more likely to be lactose intolerant, and therefore, may consume less dairy.

How Does This Affect You?

This study suggests that consuming dairy products, particularly low-fat dairy products, may lower a man’s risk of developing type 2 diabetes. The association between dairy intake and reduced diabetes risk held true regardless of other known risk factors for diabetes, including family history of diabetes, body mass index (a measure of weight in relation to height), and activity level.

Because this study was done on middle-aged men, more research is needed to know whether dairy intake has the same affect on diabetes risk in women and younger men. For now, however, the results of this study go well with the most recent dietary guidelines, which recommend three servings of fat-free or low-fat dairy per day for all adults. (One serving is equal to 8 ounces of milk or yogurt, 1.5 ounces of cheese, or 1/3 cup shredded cheese.)

In addition to possibly increasing your intake of low-fat dairy, the most important actions you can take to lower your risk of type 2 diabetes include maintaining a healthy weight, losing weight if you are overweight, exercising regularly, and reducing total fat and calorie intake.